ABSTRACT
A facile method for the synthesis of challenging medium-sized cyclic ethers has been developed via a novel oxidative rearrangement of benzylic tertiary alcohols. The reaction provides access to cyclic acetals with diverse substitution at both C2 and the aromatic ring. The unique reactivity is enabled by poly(cationic) hypervalent iodine reagents and represents the first synthetic application of this underexplored class of compounds.
ABSTRACT
2,2,3-Trisubstituted aziridines are known to undergo ring opening at the more substituted carbon under mildly basic conditions. However, the reason for the formation of the more sterically encumbered product has never been examined. Several trisubstituted aziridines, with different substitution patterns at the C-2 and C-3 carbons, were synthesized to change the electronics of the aziridine ring system. These changes had no effect on the regioselectivity of the ring-opening reaction. Using the B3LYP/6-31G* DFT basis set it was determined that the transition state for opening at the more substituted carbon proceeds at a lower energy than the transition state at the less substituted carbon.
Subject(s)
Aziridines/chemistry , Aziridines/chemical synthesis , Models, Molecular , Quantum Theory , StereoisomerismABSTRACT
The formation of substituted 1,2-diamines via nucleophilic ring opening of a trisubstituted ethynyl aziridine was performed with complete regio- and stereoselective control. Various amines with different levels of nucleophilicity were employed and gave similar results. The ring opening reaction is not limited to ethynyl aziridines, as other alkyl trisubstituted aziridines gave the same results. This method allows for the formation of unique vicinal diamines while providing a fully substituted carbon center in a stereoselective manner under mild conditions.
